1 //===- MIPS.cpp -----------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "InputFiles.h"
10 #include "OutputSections.h"
11 #include "Symbols.h"
12 #include "SyntheticSections.h"
13 #include "Target.h"
14 #include "lld/Common/ErrorHandler.h"
15 #include "llvm/BinaryFormat/ELF.h"
16
17 using namespace llvm;
18 using namespace llvm::object;
19 using namespace llvm::ELF;
20 using namespace lld;
21 using namespace lld::elf;
22
23 namespace {
24 template <class ELFT> class MIPS final : public TargetInfo {
25 public:
26 MIPS();
27 uint32_t calcEFlags() const override;
28 RelExpr getRelExpr(RelType type, const Symbol &s,
29 const uint8_t *loc) const override;
30 int64_t getImplicitAddend(const uint8_t *buf, RelType type) const override;
31 RelType getDynRel(RelType type) const override;
32 void writeGotPlt(uint8_t *buf, const Symbol &s) const override;
33 void writePltHeader(uint8_t *buf) const override;
34 void writePlt(uint8_t *buf, const Symbol &sym,
35 uint64_t pltEntryAddr) const override;
36 bool needsThunk(RelExpr expr, RelType type, const InputFile *file,
37 uint64_t branchAddr, const Symbol &s,
38 int64_t a) const override;
39 void relocate(uint8_t *loc, const Relocation &rel,
40 uint64_t val) const override;
41 bool usesOnlyLowPageBits(RelType type) const override;
42 };
43 } // namespace
44
MIPS()45 template <class ELFT> MIPS<ELFT>::MIPS() {
46 gotPltHeaderEntriesNum = 2;
47 defaultMaxPageSize = 65536;
48 pltEntrySize = 16;
49 pltHeaderSize = 32;
50 copyRel = R_MIPS_COPY;
51 pltRel = R_MIPS_JUMP_SLOT;
52 needsThunks = true;
53
54 // Set `sigrie 1` as a trap instruction.
55 write32(trapInstr.data(), 0x04170001);
56
57 if (ELFT::Is64Bits) {
58 relativeRel = (R_MIPS_64 << 8) | R_MIPS_REL32;
59 symbolicRel = R_MIPS_64;
60 tlsGotRel = R_MIPS_TLS_TPREL64;
61 tlsModuleIndexRel = R_MIPS_TLS_DTPMOD64;
62 tlsOffsetRel = R_MIPS_TLS_DTPREL64;
63 } else {
64 relativeRel = R_MIPS_REL32;
65 symbolicRel = R_MIPS_32;
66 tlsGotRel = R_MIPS_TLS_TPREL32;
67 tlsModuleIndexRel = R_MIPS_TLS_DTPMOD32;
68 tlsOffsetRel = R_MIPS_TLS_DTPREL32;
69 }
70 }
71
calcEFlags() const72 template <class ELFT> uint32_t MIPS<ELFT>::calcEFlags() const {
73 return calcMipsEFlags<ELFT>();
74 }
75
76 template <class ELFT>
getRelExpr(RelType type,const Symbol & s,const uint8_t * loc) const77 RelExpr MIPS<ELFT>::getRelExpr(RelType type, const Symbol &s,
78 const uint8_t *loc) const {
79 // See comment in the calculateMipsRelChain.
80 if (ELFT::Is64Bits || config->mipsN32Abi)
81 type &= 0xff;
82
83 switch (type) {
84 case R_MIPS_JALR:
85 // Older versions of clang would erroneously emit this relocation not only
86 // against functions (loaded from the GOT) but also against data symbols
87 // (e.g. a table of function pointers). When we encounter this, ignore the
88 // relocation and emit a warning instead.
89 if (!s.isFunc() && s.type != STT_NOTYPE) {
90 warn(getErrorLocation(loc) +
91 "found R_MIPS_JALR relocation against non-function symbol " +
92 toString(s) + ". This is invalid and most likely a compiler bug.");
93 return R_NONE;
94 }
95
96 // If the target symbol is not preemptible and is not microMIPS,
97 // it might be possible to replace jalr/jr instruction by bal/b.
98 // It depends on the target symbol's offset.
99 if (!s.isPreemptible && !(s.getVA() & 0x1))
100 return R_PC;
101 return R_NONE;
102 case R_MICROMIPS_JALR:
103 return R_NONE;
104 case R_MIPS_GPREL16:
105 case R_MIPS_GPREL32:
106 case R_MICROMIPS_GPREL16:
107 case R_MICROMIPS_GPREL7_S2:
108 return R_MIPS_GOTREL;
109 case R_MIPS_26:
110 case R_MICROMIPS_26_S1:
111 return R_PLT;
112 case R_MICROMIPS_PC26_S1:
113 return R_PLT_PC;
114 case R_MIPS_HI16:
115 case R_MIPS_LO16:
116 case R_MIPS_HIGHER:
117 case R_MIPS_HIGHEST:
118 case R_MICROMIPS_HI16:
119 case R_MICROMIPS_LO16:
120 // R_MIPS_HI16/R_MIPS_LO16 relocations against _gp_disp calculate
121 // offset between start of function and 'gp' value which by default
122 // equal to the start of .got section. In that case we consider these
123 // relocations as relative.
124 if (&s == ElfSym::mipsGpDisp)
125 return R_MIPS_GOT_GP_PC;
126 if (&s == ElfSym::mipsLocalGp)
127 return R_MIPS_GOT_GP;
128 [[fallthrough]];
129 case R_MIPS_32:
130 case R_MIPS_64:
131 case R_MIPS_GOT_OFST:
132 case R_MIPS_SUB:
133 return R_ABS;
134 case R_MIPS_TLS_DTPREL_HI16:
135 case R_MIPS_TLS_DTPREL_LO16:
136 case R_MIPS_TLS_DTPREL32:
137 case R_MIPS_TLS_DTPREL64:
138 case R_MICROMIPS_TLS_DTPREL_HI16:
139 case R_MICROMIPS_TLS_DTPREL_LO16:
140 return R_DTPREL;
141 case R_MIPS_TLS_TPREL_HI16:
142 case R_MIPS_TLS_TPREL_LO16:
143 case R_MIPS_TLS_TPREL32:
144 case R_MIPS_TLS_TPREL64:
145 case R_MICROMIPS_TLS_TPREL_HI16:
146 case R_MICROMIPS_TLS_TPREL_LO16:
147 return R_TPREL;
148 case R_MIPS_PC32:
149 case R_MIPS_PC16:
150 case R_MIPS_PC19_S2:
151 case R_MIPS_PC21_S2:
152 case R_MIPS_PC26_S2:
153 case R_MIPS_PCHI16:
154 case R_MIPS_PCLO16:
155 case R_MICROMIPS_PC7_S1:
156 case R_MICROMIPS_PC10_S1:
157 case R_MICROMIPS_PC16_S1:
158 case R_MICROMIPS_PC18_S3:
159 case R_MICROMIPS_PC19_S2:
160 case R_MICROMIPS_PC23_S2:
161 case R_MICROMIPS_PC21_S1:
162 return R_PC;
163 case R_MIPS_GOT16:
164 case R_MICROMIPS_GOT16:
165 if (s.isLocal())
166 return R_MIPS_GOT_LOCAL_PAGE;
167 [[fallthrough]];
168 case R_MIPS_CALL16:
169 case R_MIPS_GOT_DISP:
170 case R_MIPS_TLS_GOTTPREL:
171 case R_MICROMIPS_CALL16:
172 case R_MICROMIPS_TLS_GOTTPREL:
173 return R_MIPS_GOT_OFF;
174 case R_MIPS_CALL_HI16:
175 case R_MIPS_CALL_LO16:
176 case R_MIPS_GOT_HI16:
177 case R_MIPS_GOT_LO16:
178 case R_MICROMIPS_CALL_HI16:
179 case R_MICROMIPS_CALL_LO16:
180 case R_MICROMIPS_GOT_HI16:
181 case R_MICROMIPS_GOT_LO16:
182 return R_MIPS_GOT_OFF32;
183 case R_MIPS_GOT_PAGE:
184 return R_MIPS_GOT_LOCAL_PAGE;
185 case R_MIPS_TLS_GD:
186 case R_MICROMIPS_TLS_GD:
187 return R_MIPS_TLSGD;
188 case R_MIPS_TLS_LDM:
189 case R_MICROMIPS_TLS_LDM:
190 return R_MIPS_TLSLD;
191 case R_MIPS_NONE:
192 return R_NONE;
193 default:
194 error(getErrorLocation(loc) + "unknown relocation (" + Twine(type) +
195 ") against symbol " + toString(s));
196 return R_NONE;
197 }
198 }
199
getDynRel(RelType type) const200 template <class ELFT> RelType MIPS<ELFT>::getDynRel(RelType type) const {
201 if (type == symbolicRel)
202 return type;
203 return R_MIPS_NONE;
204 }
205
206 template <class ELFT>
writeGotPlt(uint8_t * buf,const Symbol &) const207 void MIPS<ELFT>::writeGotPlt(uint8_t *buf, const Symbol &) const {
208 uint64_t va = in.plt->getVA();
209 if (isMicroMips())
210 va |= 1;
211 write32(buf, va);
212 }
213
readShuffle(const uint8_t * loc)214 template <endianness E> static uint32_t readShuffle(const uint8_t *loc) {
215 // The major opcode of a microMIPS instruction needs to appear
216 // in the first 16-bit word (lowest address) for efficient hardware
217 // decode so that it knows if the instruction is 16-bit or 32-bit
218 // as early as possible. To do so, little-endian binaries keep 16-bit
219 // words in a big-endian order. That is why we have to swap these
220 // words to get a correct value.
221 uint32_t v = read32(loc);
222 if (E == llvm::endianness::little)
223 return (v << 16) | (v >> 16);
224 return v;
225 }
226
writeValue(uint8_t * loc,uint64_t v,uint8_t bitsSize,uint8_t shift)227 static void writeValue(uint8_t *loc, uint64_t v, uint8_t bitsSize,
228 uint8_t shift) {
229 uint32_t instr = read32(loc);
230 uint32_t mask = 0xffffffff >> (32 - bitsSize);
231 uint32_t data = (instr & ~mask) | ((v >> shift) & mask);
232 write32(loc, data);
233 }
234
235 template <endianness E>
writeShuffleValue(uint8_t * loc,uint64_t v,uint8_t bitsSize,uint8_t shift)236 static void writeShuffleValue(uint8_t *loc, uint64_t v, uint8_t bitsSize,
237 uint8_t shift) {
238 // See comments in readShuffle for purpose of this code.
239 uint16_t *words = (uint16_t *)loc;
240 if (E == llvm::endianness::little)
241 std::swap(words[0], words[1]);
242
243 writeValue(loc, v, bitsSize, shift);
244
245 if (E == llvm::endianness::little)
246 std::swap(words[0], words[1]);
247 }
248
249 template <endianness E>
writeMicroRelocation16(uint8_t * loc,uint64_t v,uint8_t bitsSize,uint8_t shift)250 static void writeMicroRelocation16(uint8_t *loc, uint64_t v, uint8_t bitsSize,
251 uint8_t shift) {
252 uint16_t instr = read16(loc);
253 uint16_t mask = 0xffff >> (16 - bitsSize);
254 uint16_t data = (instr & ~mask) | ((v >> shift) & mask);
255 write16(loc, data);
256 }
257
writePltHeader(uint8_t * buf) const258 template <class ELFT> void MIPS<ELFT>::writePltHeader(uint8_t *buf) const {
259 if (isMicroMips()) {
260 uint64_t gotPlt = in.gotPlt->getVA();
261 uint64_t plt = in.plt->getVA();
262 // Overwrite trap instructions written by Writer::writeTrapInstr.
263 memset(buf, 0, pltHeaderSize);
264
265 write16(buf, isMipsR6() ? 0x7860 : 0x7980); // addiupc v1, (GOTPLT) - .
266 write16(buf + 4, 0xff23); // lw $25, 0($3)
267 write16(buf + 8, 0x0535); // subu16 $2, $2, $3
268 write16(buf + 10, 0x2525); // srl16 $2, $2, 2
269 write16(buf + 12, 0x3302); // addiu $24, $2, -2
270 write16(buf + 14, 0xfffe);
271 write16(buf + 16, 0x0dff); // move $15, $31
272 if (isMipsR6()) {
273 write16(buf + 18, 0x0f83); // move $28, $3
274 write16(buf + 20, 0x472b); // jalrc $25
275 write16(buf + 22, 0x0c00); // nop
276 relocateNoSym(buf, R_MICROMIPS_PC19_S2, gotPlt - plt);
277 } else {
278 write16(buf + 18, 0x45f9); // jalrc $25
279 write16(buf + 20, 0x0f83); // move $28, $3
280 write16(buf + 22, 0x0c00); // nop
281 relocateNoSym(buf, R_MICROMIPS_PC23_S2, gotPlt - plt);
282 }
283 return;
284 }
285
286 if (config->mipsN32Abi) {
287 write32(buf, 0x3c0e0000); // lui $14, %hi(&GOTPLT[0])
288 write32(buf + 4, 0x8dd90000); // lw $25, %lo(&GOTPLT[0])($14)
289 write32(buf + 8, 0x25ce0000); // addiu $14, $14, %lo(&GOTPLT[0])
290 write32(buf + 12, 0x030ec023); // subu $24, $24, $14
291 write32(buf + 16, 0x03e07825); // move $15, $31
292 write32(buf + 20, 0x0018c082); // srl $24, $24, 2
293 } else if (ELFT::Is64Bits) {
294 write32(buf, 0x3c0e0000); // lui $14, %hi(&GOTPLT[0])
295 write32(buf + 4, 0xddd90000); // ld $25, %lo(&GOTPLT[0])($14)
296 write32(buf + 8, 0x25ce0000); // addiu $14, $14, %lo(&GOTPLT[0])
297 write32(buf + 12, 0x030ec023); // subu $24, $24, $14
298 write32(buf + 16, 0x03e07825); // move $15, $31
299 write32(buf + 20, 0x0018c0c2); // srl $24, $24, 3
300 } else {
301 write32(buf, 0x3c1c0000); // lui $28, %hi(&GOTPLT[0])
302 write32(buf + 4, 0x8f990000); // lw $25, %lo(&GOTPLT[0])($28)
303 write32(buf + 8, 0x279c0000); // addiu $28, $28, %lo(&GOTPLT[0])
304 write32(buf + 12, 0x031cc023); // subu $24, $24, $28
305 write32(buf + 16, 0x03e07825); // move $15, $31
306 write32(buf + 20, 0x0018c082); // srl $24, $24, 2
307 }
308
309 uint32_t jalrInst = config->zHazardplt ? 0x0320fc09 : 0x0320f809;
310 write32(buf + 24, jalrInst); // jalr.hb $25 or jalr $25
311 write32(buf + 28, 0x2718fffe); // subu $24, $24, 2
312
313 uint64_t gotPlt = in.gotPlt->getVA();
314 writeValue(buf, gotPlt + 0x8000, 16, 16);
315 writeValue(buf + 4, gotPlt, 16, 0);
316 writeValue(buf + 8, gotPlt, 16, 0);
317 }
318
319 template <class ELFT>
writePlt(uint8_t * buf,const Symbol & sym,uint64_t pltEntryAddr) const320 void MIPS<ELFT>::writePlt(uint8_t *buf, const Symbol &sym,
321 uint64_t pltEntryAddr) const {
322 uint64_t gotPltEntryAddr = sym.getGotPltVA();
323 if (isMicroMips()) {
324 // Overwrite trap instructions written by Writer::writeTrapInstr.
325 memset(buf, 0, pltEntrySize);
326
327 if (isMipsR6()) {
328 write16(buf, 0x7840); // addiupc $2, (GOTPLT) - .
329 write16(buf + 4, 0xff22); // lw $25, 0($2)
330 write16(buf + 8, 0x0f02); // move $24, $2
331 write16(buf + 10, 0x4723); // jrc $25 / jr16 $25
332 relocateNoSym(buf, R_MICROMIPS_PC19_S2, gotPltEntryAddr - pltEntryAddr);
333 } else {
334 write16(buf, 0x7900); // addiupc $2, (GOTPLT) - .
335 write16(buf + 4, 0xff22); // lw $25, 0($2)
336 write16(buf + 8, 0x4599); // jrc $25 / jr16 $25
337 write16(buf + 10, 0x0f02); // move $24, $2
338 relocateNoSym(buf, R_MICROMIPS_PC23_S2, gotPltEntryAddr - pltEntryAddr);
339 }
340 return;
341 }
342
343 uint32_t loadInst = ELFT::Is64Bits ? 0xddf90000 : 0x8df90000;
344 uint32_t jrInst = isMipsR6() ? (config->zHazardplt ? 0x03200409 : 0x03200009)
345 : (config->zHazardplt ? 0x03200408 : 0x03200008);
346 uint32_t addInst = ELFT::Is64Bits ? 0x65f80000 : 0x25f80000;
347
348 write32(buf, 0x3c0f0000); // lui $15, %hi(.got.plt entry)
349 write32(buf + 4, loadInst); // l[wd] $25, %lo(.got.plt entry)($15)
350 write32(buf + 8, jrInst); // jr $25 / jr.hb $25
351 write32(buf + 12, addInst); // [d]addiu $24, $15, %lo(.got.plt entry)
352 writeValue(buf, gotPltEntryAddr + 0x8000, 16, 16);
353 writeValue(buf + 4, gotPltEntryAddr, 16, 0);
354 writeValue(buf + 12, gotPltEntryAddr, 16, 0);
355 }
356
357 template <class ELFT>
needsThunk(RelExpr expr,RelType type,const InputFile * file,uint64_t branchAddr,const Symbol & s,int64_t) const358 bool MIPS<ELFT>::needsThunk(RelExpr expr, RelType type, const InputFile *file,
359 uint64_t branchAddr, const Symbol &s,
360 int64_t /*a*/) const {
361 // Any MIPS PIC code function is invoked with its address in register $t9.
362 // So if we have a branch instruction from non-PIC code to the PIC one
363 // we cannot make the jump directly and need to create a small stubs
364 // to save the target function address.
365 // See page 3-38 ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
366 if (type != R_MIPS_26 && type != R_MIPS_PC26_S2 &&
367 type != R_MICROMIPS_26_S1 && type != R_MICROMIPS_PC26_S1)
368 return false;
369 auto *f = dyn_cast_or_null<ObjFile<ELFT>>(file);
370 if (!f)
371 return false;
372 // If current file has PIC code, LA25 stub is not required.
373 if (f->getObj().getHeader().e_flags & EF_MIPS_PIC)
374 return false;
375 auto *d = dyn_cast<Defined>(&s);
376 // LA25 is required if target file has PIC code
377 // or target symbol is a PIC symbol.
378 return d && isMipsPIC<ELFT>(d);
379 }
380
381 template <class ELFT>
getImplicitAddend(const uint8_t * buf,RelType type) const382 int64_t MIPS<ELFT>::getImplicitAddend(const uint8_t *buf, RelType type) const {
383 const endianness e = ELFT::Endianness;
384 switch (type) {
385 case R_MIPS_32:
386 case R_MIPS_REL32:
387 case R_MIPS_GPREL32:
388 case R_MIPS_TLS_DTPREL32:
389 case R_MIPS_TLS_DTPMOD32:
390 case R_MIPS_TLS_TPREL32:
391 return SignExtend64<32>(read32(buf));
392 case R_MIPS_26:
393 // FIXME (simon): If the relocation target symbol is not a PLT entry
394 // we should use another expression for calculation:
395 // ((A << 2) | (P & 0xf0000000)) >> 2
396 return SignExtend64<28>(read32(buf) << 2);
397 case R_MIPS_CALL_HI16:
398 case R_MIPS_GOT16:
399 case R_MIPS_GOT_HI16:
400 case R_MIPS_HI16:
401 case R_MIPS_PCHI16:
402 return SignExtend64<16>(read32(buf)) << 16;
403 case R_MIPS_CALL16:
404 case R_MIPS_CALL_LO16:
405 case R_MIPS_GOT_LO16:
406 case R_MIPS_GPREL16:
407 case R_MIPS_LO16:
408 case R_MIPS_PCLO16:
409 case R_MIPS_TLS_DTPREL_HI16:
410 case R_MIPS_TLS_DTPREL_LO16:
411 case R_MIPS_TLS_GD:
412 case R_MIPS_TLS_GOTTPREL:
413 case R_MIPS_TLS_LDM:
414 case R_MIPS_TLS_TPREL_HI16:
415 case R_MIPS_TLS_TPREL_LO16:
416 return SignExtend64<16>(read32(buf));
417 case R_MICROMIPS_GOT16:
418 case R_MICROMIPS_HI16:
419 return SignExtend64<16>(readShuffle<e>(buf)) << 16;
420 case R_MICROMIPS_CALL16:
421 case R_MICROMIPS_GPREL16:
422 case R_MICROMIPS_LO16:
423 case R_MICROMIPS_TLS_DTPREL_HI16:
424 case R_MICROMIPS_TLS_DTPREL_LO16:
425 case R_MICROMIPS_TLS_GD:
426 case R_MICROMIPS_TLS_GOTTPREL:
427 case R_MICROMIPS_TLS_LDM:
428 case R_MICROMIPS_TLS_TPREL_HI16:
429 case R_MICROMIPS_TLS_TPREL_LO16:
430 return SignExtend64<16>(readShuffle<e>(buf));
431 case R_MICROMIPS_GPREL7_S2:
432 return SignExtend64<9>(readShuffle<e>(buf) << 2);
433 case R_MIPS_PC16:
434 return SignExtend64<18>(read32(buf) << 2);
435 case R_MIPS_PC19_S2:
436 return SignExtend64<21>(read32(buf) << 2);
437 case R_MIPS_PC21_S2:
438 return SignExtend64<23>(read32(buf) << 2);
439 case R_MIPS_PC26_S2:
440 return SignExtend64<28>(read32(buf) << 2);
441 case R_MIPS_PC32:
442 return SignExtend64<32>(read32(buf));
443 case R_MICROMIPS_26_S1:
444 return SignExtend64<27>(readShuffle<e>(buf) << 1);
445 case R_MICROMIPS_PC7_S1:
446 return SignExtend64<8>(read16(buf) << 1);
447 case R_MICROMIPS_PC10_S1:
448 return SignExtend64<11>(read16(buf) << 1);
449 case R_MICROMIPS_PC16_S1:
450 return SignExtend64<17>(readShuffle<e>(buf) << 1);
451 case R_MICROMIPS_PC18_S3:
452 return SignExtend64<21>(readShuffle<e>(buf) << 3);
453 case R_MICROMIPS_PC19_S2:
454 return SignExtend64<21>(readShuffle<e>(buf) << 2);
455 case R_MICROMIPS_PC21_S1:
456 return SignExtend64<22>(readShuffle<e>(buf) << 1);
457 case R_MICROMIPS_PC23_S2:
458 return SignExtend64<25>(readShuffle<e>(buf) << 2);
459 case R_MICROMIPS_PC26_S1:
460 return SignExtend64<27>(readShuffle<e>(buf) << 1);
461 case R_MIPS_64:
462 case R_MIPS_TLS_DTPMOD64:
463 case R_MIPS_TLS_DTPREL64:
464 case R_MIPS_TLS_TPREL64:
465 case (R_MIPS_64 << 8) | R_MIPS_REL32:
466 return read64(buf);
467 case R_MIPS_COPY:
468 return config->is64 ? read64(buf) : read32(buf);
469 case R_MIPS_NONE:
470 case R_MIPS_JUMP_SLOT:
471 case R_MIPS_JALR:
472 // These relocations are defined as not having an implicit addend.
473 return 0;
474 default:
475 internalLinkerError(getErrorLocation(buf),
476 "cannot read addend for relocation " + toString(type));
477 return 0;
478 }
479 }
480
481 static std::pair<uint32_t, uint64_t>
calculateMipsRelChain(uint8_t * loc,RelType type,uint64_t val)482 calculateMipsRelChain(uint8_t *loc, RelType type, uint64_t val) {
483 // MIPS N64 ABI packs multiple relocations into the single relocation
484 // record. In general, all up to three relocations can have arbitrary
485 // types. In fact, Clang and GCC uses only a few combinations. For now,
486 // we support two of them. That is allow to pass at least all LLVM
487 // test suite cases.
488 // <any relocation> / R_MIPS_SUB / R_MIPS_HI16 | R_MIPS_LO16
489 // <any relocation> / R_MIPS_64 / R_MIPS_NONE
490 // The first relocation is a 'real' relocation which is calculated
491 // using the corresponding symbol's value. The second and the third
492 // relocations used to modify result of the first one: extend it to
493 // 64-bit, extract high or low part etc. For details, see part 2.9 Relocation
494 // at the https://dmz-portal.mips.com/mw/images/8/82/007-4658-001.pdf
495 RelType type2 = (type >> 8) & 0xff;
496 RelType type3 = (type >> 16) & 0xff;
497 if (type2 == R_MIPS_NONE && type3 == R_MIPS_NONE)
498 return std::make_pair(type, val);
499 if (type2 == R_MIPS_64 && type3 == R_MIPS_NONE)
500 return std::make_pair(type2, val);
501 if (type2 == R_MIPS_SUB && (type3 == R_MIPS_HI16 || type3 == R_MIPS_LO16))
502 return std::make_pair(type3, -val);
503 error(getErrorLocation(loc) + "unsupported relocations combination " +
504 Twine(type));
505 return std::make_pair(type & 0xff, val);
506 }
507
isBranchReloc(RelType type)508 static bool isBranchReloc(RelType type) {
509 return type == R_MIPS_26 || type == R_MIPS_PC26_S2 ||
510 type == R_MIPS_PC21_S2 || type == R_MIPS_PC16;
511 }
512
isMicroBranchReloc(RelType type)513 static bool isMicroBranchReloc(RelType type) {
514 return type == R_MICROMIPS_26_S1 || type == R_MICROMIPS_PC16_S1 ||
515 type == R_MICROMIPS_PC10_S1 || type == R_MICROMIPS_PC7_S1;
516 }
517
518 template <class ELFT>
fixupCrossModeJump(uint8_t * loc,RelType type,uint64_t val)519 static uint64_t fixupCrossModeJump(uint8_t *loc, RelType type, uint64_t val) {
520 // Here we need to detect jump/branch from regular MIPS code
521 // to a microMIPS target and vice versa. In that cases jump
522 // instructions need to be replaced by their "cross-mode"
523 // equivalents.
524 const endianness e = ELFT::Endianness;
525 bool isMicroTgt = val & 0x1;
526 bool isCrossJump = (isMicroTgt && isBranchReloc(type)) ||
527 (!isMicroTgt && isMicroBranchReloc(type));
528 if (!isCrossJump)
529 return val;
530
531 switch (type) {
532 case R_MIPS_26: {
533 uint32_t inst = read32(loc) >> 26;
534 if (inst == 0x3 || inst == 0x1d) { // JAL or JALX
535 writeValue(loc, 0x1d << 26, 32, 0);
536 return val;
537 }
538 break;
539 }
540 case R_MICROMIPS_26_S1: {
541 uint32_t inst = readShuffle<e>(loc) >> 26;
542 if (inst == 0x3d || inst == 0x3c) { // JAL32 or JALX32
543 val >>= 1;
544 writeShuffleValue<e>(loc, 0x3c << 26, 32, 0);
545 return val;
546 }
547 break;
548 }
549 case R_MIPS_PC26_S2:
550 case R_MIPS_PC21_S2:
551 case R_MIPS_PC16:
552 case R_MICROMIPS_PC16_S1:
553 case R_MICROMIPS_PC10_S1:
554 case R_MICROMIPS_PC7_S1:
555 // FIXME (simon): Support valid branch relocations.
556 break;
557 default:
558 llvm_unreachable("unexpected jump/branch relocation");
559 }
560
561 error(getErrorLocation(loc) +
562 "unsupported jump/branch instruction between ISA modes referenced by " +
563 toString(type) + " relocation");
564 return val;
565 }
566
567 template <class ELFT>
relocate(uint8_t * loc,const Relocation & rel,uint64_t val) const568 void MIPS<ELFT>::relocate(uint8_t *loc, const Relocation &rel,
569 uint64_t val) const {
570 const endianness e = ELFT::Endianness;
571 RelType type = rel.type;
572
573 if (ELFT::Is64Bits || config->mipsN32Abi)
574 std::tie(type, val) = calculateMipsRelChain(loc, type, val);
575
576 // Detect cross-mode jump/branch and fix instruction.
577 val = fixupCrossModeJump<ELFT>(loc, type, val);
578
579 // Thread pointer and DRP offsets from the start of TLS data area.
580 // https://www.linux-mips.org/wiki/NPTL
581 if (type == R_MIPS_TLS_DTPREL_HI16 || type == R_MIPS_TLS_DTPREL_LO16 ||
582 type == R_MIPS_TLS_DTPREL32 || type == R_MIPS_TLS_DTPREL64 ||
583 type == R_MICROMIPS_TLS_DTPREL_HI16 ||
584 type == R_MICROMIPS_TLS_DTPREL_LO16) {
585 val -= 0x8000;
586 }
587
588 switch (type) {
589 case R_MIPS_32:
590 case R_MIPS_GPREL32:
591 case R_MIPS_TLS_DTPREL32:
592 case R_MIPS_TLS_TPREL32:
593 write32(loc, val);
594 break;
595 case R_MIPS_64:
596 case R_MIPS_TLS_DTPREL64:
597 case R_MIPS_TLS_TPREL64:
598 write64(loc, val);
599 break;
600 case R_MIPS_26:
601 writeValue(loc, val, 26, 2);
602 break;
603 case R_MIPS_GOT16:
604 // The R_MIPS_GOT16 relocation's value in "relocatable" linking mode
605 // is updated addend (not a GOT index). In that case write high 16 bits
606 // to store a correct addend value.
607 if (config->relocatable) {
608 writeValue(loc, val + 0x8000, 16, 16);
609 } else {
610 checkInt(loc, val, 16, rel);
611 writeValue(loc, val, 16, 0);
612 }
613 break;
614 case R_MICROMIPS_GOT16:
615 if (config->relocatable) {
616 writeShuffleValue<e>(loc, val + 0x8000, 16, 16);
617 } else {
618 checkInt(loc, val, 16, rel);
619 writeShuffleValue<e>(loc, val, 16, 0);
620 }
621 break;
622 case R_MIPS_CALL16:
623 case R_MIPS_GOT_DISP:
624 case R_MIPS_GOT_PAGE:
625 case R_MIPS_GPREL16:
626 case R_MIPS_TLS_GD:
627 case R_MIPS_TLS_GOTTPREL:
628 case R_MIPS_TLS_LDM:
629 checkInt(loc, val, 16, rel);
630 [[fallthrough]];
631 case R_MIPS_CALL_LO16:
632 case R_MIPS_GOT_LO16:
633 case R_MIPS_GOT_OFST:
634 case R_MIPS_LO16:
635 case R_MIPS_PCLO16:
636 case R_MIPS_TLS_DTPREL_LO16:
637 case R_MIPS_TLS_TPREL_LO16:
638 writeValue(loc, val, 16, 0);
639 break;
640 case R_MICROMIPS_GPREL16:
641 case R_MICROMIPS_TLS_GD:
642 case R_MICROMIPS_TLS_LDM:
643 checkInt(loc, val, 16, rel);
644 writeShuffleValue<e>(loc, val, 16, 0);
645 break;
646 case R_MICROMIPS_CALL16:
647 case R_MICROMIPS_CALL_LO16:
648 case R_MICROMIPS_LO16:
649 case R_MICROMIPS_TLS_DTPREL_LO16:
650 case R_MICROMIPS_TLS_GOTTPREL:
651 case R_MICROMIPS_TLS_TPREL_LO16:
652 writeShuffleValue<e>(loc, val, 16, 0);
653 break;
654 case R_MICROMIPS_GPREL7_S2:
655 checkInt(loc, val, 7, rel);
656 writeShuffleValue<e>(loc, val, 7, 2);
657 break;
658 case R_MIPS_CALL_HI16:
659 case R_MIPS_GOT_HI16:
660 case R_MIPS_HI16:
661 case R_MIPS_PCHI16:
662 case R_MIPS_TLS_DTPREL_HI16:
663 case R_MIPS_TLS_TPREL_HI16:
664 writeValue(loc, val + 0x8000, 16, 16);
665 break;
666 case R_MICROMIPS_CALL_HI16:
667 case R_MICROMIPS_GOT_HI16:
668 case R_MICROMIPS_HI16:
669 case R_MICROMIPS_TLS_DTPREL_HI16:
670 case R_MICROMIPS_TLS_TPREL_HI16:
671 writeShuffleValue<e>(loc, val + 0x8000, 16, 16);
672 break;
673 case R_MIPS_HIGHER:
674 writeValue(loc, val + 0x80008000, 16, 32);
675 break;
676 case R_MIPS_HIGHEST:
677 writeValue(loc, val + 0x800080008000, 16, 48);
678 break;
679 case R_MIPS_JALR:
680 val -= 4;
681 // Replace jalr/jr instructions by bal/b if the target
682 // offset fits into the 18-bit range.
683 if (isInt<18>(val)) {
684 switch (read32(loc)) {
685 case 0x0320f809: // jalr $25 => bal sym
686 write32(loc, 0x04110000 | ((val >> 2) & 0xffff));
687 break;
688 case 0x03200008: // jr $25 => b sym
689 write32(loc, 0x10000000 | ((val >> 2) & 0xffff));
690 break;
691 }
692 }
693 break;
694 case R_MICROMIPS_JALR:
695 // Ignore this optimization relocation for now
696 break;
697 case R_MIPS_PC16:
698 checkAlignment(loc, val, 4, rel);
699 checkInt(loc, val, 18, rel);
700 writeValue(loc, val, 16, 2);
701 break;
702 case R_MIPS_PC19_S2:
703 checkAlignment(loc, val, 4, rel);
704 checkInt(loc, val, 21, rel);
705 writeValue(loc, val, 19, 2);
706 break;
707 case R_MIPS_PC21_S2:
708 checkAlignment(loc, val, 4, rel);
709 checkInt(loc, val, 23, rel);
710 writeValue(loc, val, 21, 2);
711 break;
712 case R_MIPS_PC26_S2:
713 checkAlignment(loc, val, 4, rel);
714 checkInt(loc, val, 28, rel);
715 writeValue(loc, val, 26, 2);
716 break;
717 case R_MIPS_PC32:
718 writeValue(loc, val, 32, 0);
719 break;
720 case R_MICROMIPS_26_S1:
721 case R_MICROMIPS_PC26_S1:
722 checkInt(loc, val, 27, rel);
723 writeShuffleValue<e>(loc, val, 26, 1);
724 break;
725 case R_MICROMIPS_PC7_S1:
726 checkInt(loc, val, 8, rel);
727 writeMicroRelocation16<e>(loc, val, 7, 1);
728 break;
729 case R_MICROMIPS_PC10_S1:
730 checkInt(loc, val, 11, rel);
731 writeMicroRelocation16<e>(loc, val, 10, 1);
732 break;
733 case R_MICROMIPS_PC16_S1:
734 checkInt(loc, val, 17, rel);
735 writeShuffleValue<e>(loc, val, 16, 1);
736 break;
737 case R_MICROMIPS_PC18_S3:
738 checkInt(loc, val, 21, rel);
739 writeShuffleValue<e>(loc, val, 18, 3);
740 break;
741 case R_MICROMIPS_PC19_S2:
742 checkInt(loc, val, 21, rel);
743 writeShuffleValue<e>(loc, val, 19, 2);
744 break;
745 case R_MICROMIPS_PC21_S1:
746 checkInt(loc, val, 22, rel);
747 writeShuffleValue<e>(loc, val, 21, 1);
748 break;
749 case R_MICROMIPS_PC23_S2:
750 checkInt(loc, val, 25, rel);
751 writeShuffleValue<e>(loc, val, 23, 2);
752 break;
753 default:
754 llvm_unreachable("unknown relocation");
755 }
756 }
757
usesOnlyLowPageBits(RelType type) const758 template <class ELFT> bool MIPS<ELFT>::usesOnlyLowPageBits(RelType type) const {
759 return type == R_MIPS_LO16 || type == R_MIPS_GOT_OFST ||
760 type == R_MICROMIPS_LO16;
761 }
762
763 // Return true if the symbol is a PIC function.
isMipsPIC(const Defined * sym)764 template <class ELFT> bool elf::isMipsPIC(const Defined *sym) {
765 if (!sym->isFunc())
766 return false;
767
768 if (sym->stOther & STO_MIPS_PIC)
769 return true;
770
771 if (!sym->section)
772 return false;
773
774 InputFile *file = cast<InputSectionBase>(sym->section)->file;
775 if (!file || file->isInternal())
776 return false;
777
778 return cast<ObjFile<ELFT>>(file)->getObj().getHeader().e_flags & EF_MIPS_PIC;
779 }
780
getMipsTargetInfo()781 template <class ELFT> TargetInfo *elf::getMipsTargetInfo() {
782 static MIPS<ELFT> target;
783 return ⌖
784 }
785
786 template TargetInfo *elf::getMipsTargetInfo<ELF32LE>();
787 template TargetInfo *elf::getMipsTargetInfo<ELF32BE>();
788 template TargetInfo *elf::getMipsTargetInfo<ELF64LE>();
789 template TargetInfo *elf::getMipsTargetInfo<ELF64BE>();
790
791 template bool elf::isMipsPIC<ELF32LE>(const Defined *);
792 template bool elf::isMipsPIC<ELF32BE>(const Defined *);
793 template bool elf::isMipsPIC<ELF64LE>(const Defined *);
794 template bool elf::isMipsPIC<ELF64BE>(const Defined *);
795